/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.bff.gaia.unified.sdk.coders;



import com.bff.gaia.unified.sdk.util.VarInt;

import com.bff.gaia.unified.sdk.values.TypeDescriptor;



import java.io.*;

import java.util.Collections;

import java.util.List;



/**

 * A {@link Coder} that encodes {@link Long Longs} using between 1 and 10 bytes. Negative numbers

 * always take 10 bytes, so {@link BigEndianLongCoder} may be preferable for longs that are known to

 * often be large or negative.

 */

public class VarLongCoder extends StructuredCoder<Long> {

  public static VarLongCoder of() {

    return INSTANCE;

  }



  /////////////////////////////////////////////////////////////////////////////



  private static final VarLongCoder INSTANCE = new VarLongCoder();

  private static final TypeDescriptor<Long> TYPE_DESCRIPTOR = new TypeDescriptor<Long>() {};



  private VarLongCoder() {}



  @Override

  public void encode(Long value, OutputStream outStream) throws IOException, CoderException {

    if (value == null) {

      throw new CoderException("cannot encode a null Long");

    }

    VarInt.encode(value, outStream);

  }



  @Override

  public Long decode(InputStream inStream) throws IOException, CoderException {

    try {

      return VarInt.decodeLong(inStream);

    } catch (EOFException | UTFDataFormatException exn) {

      // These exceptions correspond to decoding problems, so change

      // what kind of exception they're branded as.

      throw new CoderException(exn);

    }

  }



  @Override

  public List<? extends Coder<?>> getCoderArguments() {

    return Collections.emptyList();

  }



  @Override

  public void verifyDeterministic() {}



  /**

   * {@inheritDoc}

   *

   * @return {@code true}. {@link VarLongCoder} is injective.

   */

  @Override

  public boolean consistentWithEquals() {

    return true;

  }



  /**

   * {@inheritDoc}

   *

   * @return {@code true}. {@link #getEncodedElementByteSize} is cheap.

   */

  @Override

  public boolean isRegisterByteSizeObserverCheap(Long value) {

    return true;

  }



  @Override

  public TypeDescriptor<Long> getEncodedTypeDescriptor() {

    return TYPE_DESCRIPTOR;

  }



  @Override

  protected long getEncodedElementByteSize(Long value) throws Exception {

    if (value == null) {

      throw new CoderException("cannot encode a null Long");

    }

    return VarInt.getLength(value);

  }

}